1. Field of the Invention
The present invention relates to locking devices and, more particularly, to combination door latching and locking mechanisms.
2. Description of the Prior Art
In the past, the access door for the housings of pad-mounted power transformers have included the well known three-point latching system actuated by rotation of a door handle which may be padlocked in its closed position. In addition to these regular locking provisions, further tamperproof devices are used to secure the high voltage access door of these housings to assure that only authorized electric utility employees are able to open these doors. One such device which is commonly used and which is required by the R.E.A. specifications for these housings, is a penta-head threaded bolt held captive in a circular recessed portion of the access door and engaging with a retaining nut held by the door frame to thus secure the access door to the housing, which can only be turned by inserting a special socket tool into the door recess over the five-sided bolt head. Thus, to secure this door, this special bolt must be threaded into a blind nut held by the door frame; consequently, slight misalignments between the door and its frame, which would otherwise be permissible, make it very difficult, if not impossible, to properly secure this bolt to its retaining nut.